NO158427B - Aqueous, enzyme-containing detergent mixture. - Google Patents

Description

The invention relates to an aqueous, enzymatic, liquid detergent mixture which, among other things, contains a stabilizing agent for aqueous, enzyme-containing preparations.

It is well known that enzymes, when included in aqueous media, are often prone to lose their activity when stored for long periods of time. This is especially the case when the aqueous media also contain other ingredients that can accelerate the deactivation of enzymes. This is e.g. often the case if the aqueous media are aqueous, liquid detergent mixtures.

According to the state of the art, numerous have been made

proposal regarding enzyme stabilizers in aqueous enzyme-containing liquid detergent mixtures. Such enzyme stabilizing systems often comprise a polyol, e.g. glycerol or sorbitol. We have recently proposed, as an enzyme stabilizing system, a mixture of polyol and a boron compound in our Dutch Patent Application No. 7711925, filed May 3, 1978.

Another proposal is made in British Patent No. 2,021,142 for the use of a mixture of a polyol and a sulfur-containing antioxidant salt as an enzyme stabilizing mixture.

We have now found that the use of certain dicarboxylic acids instead of the polyol in the above mentioned systems likewise produces an enzyme stabilizing effect. In some cases, this effect is even superior to that achieved with the polyol-containing systems.

The invention therefore relates to an aqueous, enzymatic,

liquid detergent mixture containing in an aqueous medium 1-60% by weight of a detergent active material, 1-60% by weight of a detergent builder, 0.001-10% by weight of enzymes and an enzyme stabilizing system containing (a) 1-15% by weight of a inorganic boron compound and/or 2-20% by weight of a reducing alkali metal salt having an oxygen-containing sulfur anion, and the detergent mixture is characterized in that, in addition to the enzyme stabilizing system, it contains (b) 1.0-10% by weight of a dicarboxylic acid with the formula COOH-(CHOH)a~(CH2)b~(CHOH) -

(CH2)d-COOH, where a, b, c and d are an integer from 0-4, as well as the alkali metal, ammonium, alkanolamine or alkaline earth metal salts thereof. When a=c=0 and gb=d=l, the corresponding dicarboxylic acid can also be unsaturated.

More particularly, the invention relates to aqueous, liquid enzyme-containing detergent mixtures comprising the above-mentioned mixture of (a) and (b) as an enzyme stabilizing system.

Component (a) can consist of boric acid, boron oxide or an alkali metal borate. Typical examples of alkali metal borates are sodium and potassium, -ortho-, -pyro- and -meta-borates, -poly-borates and borax. Borax is the preferred alkali metal borate.

If component (a) consists of boric acid, boric oxide or an alkali metal borate, then the amount of it is, as mentioned, 1-15, preferably 3-10, weight% calculated on the entire aqueous enzyme-containing mixture.

Component (a) can also consist of a reducing alkali metal salt which has an oxygen-containing sulfur anion where a and b are whole numbers from 1 to 8. Typical examples of such reducing salts (which have an antioxidant effect) are sodium and potassium sulphites , -bisulphites, -metabisulphites and -thiosulphates. Sodium sulfite is the preferred reducing alkali metal salt.

If component (a) consists of the reducing alkali metal salt, then the amount of it is, as mentioned, 2-20, preferably 5-15, wt% calculated on the final aqueous, enzyme-containing mixture.

Component (a) can also consist of mixtures of the various specified ingredients.

Component (b) consists of a dicarboxylic acid of the above general formula or mixtures of these acids. Instead of the acids, the anhydrides can be used, or alkali metal,

the ammonium, alkanolamine or alkali metal salts of these acids. Typical examples of suitable dicarboxylic acids are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartronic acid, malic acid, tartaric acid, xylar acid, arabimaric acid, glucaric acid, mucinic acid and saccharinic acid. In general, when a:c = 0, the carboxylic acids of the general formula where b + d =0-2 are preferred

rather than the one where b + d = 3-4, and if b+d=0, then +c is preferably 4. When a=c=Oogb=d=l then the corresponding unsaturated dicarboxylic acid, namely maleic acid or fumaric acid, can also be used.

The amount of the acid (e) used is, as mentioned, 1.0-10, preferably 2-10, % by weight calculated on the final aqueous enzyme-containing mixture. Succinic acid or saccharin acid or the alkali metal or alkanolamine salts thereof are the preferred compounds, since they provide an enzyme stabilizing effect equal to or superior to the effect obtained with the corresponding polyol-containing systems. As alkanolamine salts, the mono-, di- or triethanolamine salts can be used as well as the corresponding isopropanolamine salts. The salts of the acids can also be formed in situ in the final mixture by neutralization with the required base.

The preferred enzyme stabilizing system according to the invention comprises a mixture of sodium sulphite, borax and succinic acid or disodium succinate.

The enzymes to be incorporated into the detergent mixture according to the invention can be proteolytic, lyolytic, amylolytic and cellulolytic enzymes as well as mixtures of these. They can be of any suitable origin, e.g. vegetable, animal, bacterial, fungal and yeast origin. However, their choice is governed by several factors, e.g. pH activity and/or stability optima, thermostability, stability towards active detergents, builders, etc. In this respect, bacterial or fungal enzymes are preferred, e.g. bacterial amylases and proteases, as well as fungal cellulases.

Although the liquid products according to the invention may have a near neutral pH value, the invention is of particular use for enymatic liquid detergents with a pH of 7.5 or higher, especially those that incorporate bacterial proteases whose pH optima lies in the range between 8 .0 and 11.0, but it should be understood that enzymes with a slightly lower or higher pH optimum can also be used in the mixtures according to the invention and benefit from it.

Suitable examples of proteases are the subtilisins obtained from particular strains of B. subtilis and B. licheniformis, e.g. the commercially available subtilisins "Maxatase" and "Alcalase".

As indicated above, the invention is of particular use for enzymatic liquid detergents incorporating enzymes with pH activity and/or stability optima above 8.0, such enzymes being commonly called highly alkaline enzymes.

Particularly suitable are proteases obtained from strains of Bacillus, with maximum activity throughout the pH range 8-12, which are sold under the registered trademarks "Esperase" and "Savinase".

Production of this enzyme and analogous enzymes is described in British patent document no. 1,243,784.

Highly alkaline amylases and cellulases can also be used, e.g. α-amylases obtained from a particular strain of B. licheniformis, described in more detail in British Patent No. 1,296,839.

The enzymes can be mixed in any suitable form, e.g. as granules (marums, prills etc), or as a liquid concentrate. The granulate form often has advantages.

The amount of enzymes in the liquid mixture can, as mentioned, vary from 0.001 to 10% by weight, preferably from 0.01 to 5% by weight.

The liquid detergent mixtures according to the invention also comprise, as an essential ingredient, a detergent active material, which can be an alkali metal or alkanolamine soap or a c-io~C24-^acetic acid" including polymerized fatty acids, or an anionic, non-ionic, cationic , zwitterionic or amphoteric synthetic detergent, or mixtures of any of these.

Examples of anionic synthetic detergents are salts (including sodium, potassium, ammonium and substituted-ammonium salts, e.g. the mono-, di- and triethanolamine salts) of c^~^ 20~ alkylbenzene sulfonates, Cg-C22 -Primary or secondary alkane sulfonates, C8-C4-olefin sulfonates, sulfonated polycarboxylic acids, produced by sulfonation of the pyrolyzed product of alkaline earth metal citrates, e.g. as described in British Patent No. 1,082,179, C8-C22-alkyl sulfates, C8-C4-alkyl polyglycol ether sulfates (containing up to 10 moles of ethylene oxide);. additional examples are described in "Surface Active Agents and Detergents" (Vols. 1 and II) by Schwartz, Perry and Berch.

Examples of non-ionic synthetic detergents are the condensation products of ethylene oxide, propylene oxide and/or butylene oxide with Cg-Cj g-alkylphenols, Cg-Cj g-primary or secondary aliphatic alcohols, Cg-Cj g-fatty acid amides; further examples of nonionic material include tertiary amine oxides with one C 8 -C 7 alkyl chain and two C 7 alkyl chains. The above reference also describes further examples of non-ionic material.

The average number of molecules of ethylene oxide and/or propylene oxide present in the above non-ionic material ranges from 1-30; mixtures of different non-ionic materials, including mixtures of non-ionic materials with a lower and higher degree of alkylation, can also be used.

Examples of cationic detergents are the quaternary ammonium compounds, for example alkyldimethylammonium halides, but such cationic materials are less preferred for incorporation into enzymatic detergent mixtures.

Examples of amphoteric or zwitterionic detergents are N-alkyl amino acids, sulfobetaines, condensation products of fatty acids with protein hydrolysates, but due to their relatively high price they are usually used in combination with an anionic or a non-ionic detergent. Mixtures of the different types of detergent-active material can also be used, and preference is given to mixtures of an anionic and a non-ionic detergent-active material. Soaps (in the form of sodium, potassium and substituted ammonium salts) of fatty acids can also be used, preferably in conjunction with an anionic and/or a non-ionic synthetic detergent.

The quantity of the detergent-active material is, as mentioned, 1-60%, preferably 2-40% and particularly preferably 5-25%; when

mixtures of, for example, anionic and non-ionic material are used, the relative weight ratio varies from 10:1 to 1:10, preferably from 6:1 to 1:6. If a soap is also incorporated, the amount of this is 1-40% by weight. The liquid products according to the invention can further contain up to 60% of a pas-

sending builders, for example sodium, potassium and ammonium or substituted -ammonium pyro- and tripolyphosphates, -ethylenediamine tetraacetates, -nitrile triacetates, -ether polycarboxylates, -citrates, -carbonates, -orthophosphates, zeolites, carboxymethyl oxysuccinate, etc. Particularly preferred are the polyphosphate building salts, nitrile triacetates, citrates, zeolites, and mixtures thereof. In general, the builders are present in an amount of 1-60, preferably 5-50, and particularly preferred 5-30, weight % calculated on the final mixture.

The amount of water present in the detergent mixtures

according to the invention varies from 5 to 70% by weight.

Other conventional materials may also be present in liquid detergent compositions according to the invention, for example soil blocking agents, hydrotropes, corrosion inhibitors, dyes, perfumes, silicates, optical brighteners, suds suppressors, for example silicones, germicides, anti-staining agents , opacifying agents, fabric softeners, oxygen-releasing bleaching agents, for example hydrogen peroxide, sodium perborate or percarbonate, dispersophthalic anhydride, with or without bleach precursors, buffers and the like. If the product contains a builder, it can sometimes be advantageous to include a suspension stabilizer in the mixture so that satisfactory phase stability is obtained. Such stabilizers include natural or synthetic polymers.

Suitable examples of such suspension stabilizers are polyacrylates, copolymers of maleic anhydride and ethylene or vinyl methyl ether, as well as polymers of acrylic acid, crosslinked with no more than 10% of a vinyl group-containing crosslinker, for example polymers of acrylic acid, crosslinked with approx. 1% of a polyallyl ether of sucrose which has an average of approx. 5.8 alkyl groups for each sucrose molecule. Examples of the latter are commercially available products, available under the registered trademark "Carbopol".

Generally, if a suspension stabilizer is required, it will be included in an amount of 0.1-2, usually 0.25-1.% by weight of the final mixture.

In what follows, the invention will be illustrated by means of examples. In the examples, all percentages indicate weight of the final mixture.

The pH value of the final mixture is close to neutral, preferably 7.5 or higher, and is, if necessary, buffered to a value within said range by adding a suitable buffer system. The pH value of the washing bath, when the mixture is used, is approx. 1 pH unit higher than the above values at a use concentration of approx. 1%.

Example 1

The following mixture was prepared:

x, y and z were varied, giving a series of mixtures 1-5.

The products were stored at 37°C, and the residual enzymatic activity (RA) was measured at weekly intervals.

The following results were obtained:

The same mixture, but with 5% glycerol instead of succinic acid, had an RA after 8 weeks of 80%. The system where y = z = 0% had an RA of 36% after 1 week, and when x = z = 0%, an RA of 1% after 1 week.

The same mixture, but with 5% glycerol instead of succinic acid, had an RA after 4 weeks of 27%.

The same mixture, but with 5% adipic or glutaric acid instead of succinic acid, had an RA after 1 week of 40%. (The glutaric acid was added as glutaric anhydride).

For comparison, the same products, but with 2.5 or 5% glycerol instead of succinic acid and 7.5% sodium sulphite:

x = 2.5 or 5

y = 0

z = 7.5

had an RA after 4 weeks of 60%; same mixture, but with only 7.5% sulphite:

x = 0

y = 0

z = 7.5

had an RA of 32% after 1 week.

The same mixture, but with 5% glycerol instead of saccharin acid, had an RA after 8 weeks of 80%.

Claims (3)

1. Aqueous, enzymatic, liquid detergent composition containing, in an aqueous medium, 1-60% by weight of a detergent active material, 1-60% by weight of a detergent builder, 0.001-10% by weight of enzymes and an enzyme stabilizing system containing 1-15 % by weight of an inorganic boron compound and/or 2-20% by weight of a reducing alkali metal salt having an oxygen-containing sulfur anion, characterized in that the detergent mixture, in addition to the enzyme stabilizing system, also contains 1.0-10% by weight of a dicarboxylic acid with the formula COOH-(CHOH) a - (CH z ~), d -(CHOH) c -(CH-) d,-COOH, where a, b, c and d are an integer from 0-4, as well as alkali metal -, the ammonium, alkanolamine or alkaline earth metal salts thereof, whereby, when a=c=0 andb=d=1, the corresponding dicarboxylic acid may also be unsaturated. 2. Mixture as stated in claim 1, characterized in that 2-5% by weight of the dicarboxylic acid is present. 3. Mixture as specified in claim 2, characterized in that the enzyme stabilizer consists of a mixture of borax, sodium sulphite and succinic acid.